Flashing incandescent lamp with bimetallic filament support



Feb. 3, 1953 s. G. OHLUND 2,627,590

FLASHING INCANDESCENT LAMP WITH BI-METALLIC FILAMENT SUPPORT Filed June5, 1951 7 l ii 46 lNVEN ATTORNEY Patented Feb. 3, 1953 UNITED STATESPATENT OFFICE Selfrid Gunnar fihlund, Enskede, Sweden Application June5, 1951, Serial No. 229,888 In Sweden June 11, 1949 7 Claims.

This invention relates to an electric incandescent lamp or dischargelamp with an incandescent body supported by a lead-in wire and one orseveral supporting wires, the lamp being provided with a built-inbimetal breaker in order to obtain short-circuiting of one or severalparts of the incandescent body.

Arrangements with such thermic relays are known, as a matter of fact,for obtaining flashing lamps. Ehe invention aims at a simplearrangement, by means of which a breaking device operating with utmostreliability is obtained. The invention is characterized by aconstruction in which on at least one of the lead-in or support wires ofthe lamp a bimetal strip connected with the incandescent body is mountedand so arranged that when heated it will bend downwardly to anotherlead-in or supporting wire to shcrtcircuit the intermediate incandescentbody portion.

In accordance with the present invention heat from the incandescent bodyportion, transmitted to the bimetal strip substantially by conduction,causes the latter to make a contact movement, whereas in previousdevices of the same general character heat has been transmitted to thebimetal elment by radiation. Since the tempera ture difference betweenthe incandescent body or filament of the lamp when the latter isenergized and when it is cold is very great, a very strong and reliableaction of the bimetal relay is obtained with the present invention.

The invention is further illustrated by a few examples of design shownin the accompanying drawing.

Fig. 1 shows an incandescent lamp with an incandescent body arranged ininverted V-shape, one leg of which is induced to light periodically.

Fig. 2 shows a similar lamp with both legs of the incandescent bodyprovided with twinkling devices.

Fig. 3 shows a body arranged in inverted U- shape with twinkling deviceson each leg.

The examples shown in Figs. 1 and 2 are incandescent lamps intended foruse in connection with Christmas tree illumination. The usual series 11-lumination sets for this purpose contain sixteen series-connected lamps.It is sufficient for obtaining a good imitation of burning candles tolet a few, for instance three of the series-connected lamps consist oflamps with twinkling devices. With the arrangement shown in Fig. 2 itmay happen, of course, that both legs are short-circulted at the sametime; but this will not do any harm in series-connection together withlamps without twinkling relays.

The Christmas tree lamp shown in Fig. 1 consists of an envelope 3elongated to a point and closed at the bottom by fusion 9, through whichlead-in wires I and i2 pass. The lead-in wires are downwardly connectedwith a socket Ill and at the top surrounded by a pearl foot I! andbridged by a so-called supporting bridge 8, which, for instance,consists of an oxidized aluminum ribbon. To'lead-in wire I is welded abimetal strip 6. The incandescent body of the lamp consists of atungsten coil arranged in inverted V- shape. The top 2 of theincandescent body is carried in an eye I on a supporting wire 5,attached to foot H by fusing. One of the ends of the incandescent bodyis fastened to lead-in wire [2, and the other one to bimetal strip 6. Tothe supporting wire 5 is fused by welding a small piece of wire I 3directed towards bimetal strip 6. When the lamp is turned on, the leg ofthe incandescent body attached to bimetal strip 6 conveys its heat tobimetal strip 6, which thereby is induced to bend inwardly againstcontact l3, when the leg in question will become extinct. The bimetalstrip is cooled down and draws away from contact i3, and the proceduredescribed is repeated.

In the case of the Christmas tree lamp as shown in Fig. 2, both lead-inwires are fitted with bimetal strips 6, each connected to one end ofincandescent body 4. Supporting wire 5 is provided with an eye I4serving as a counter-contact for bimetal strips 6.

In the case of the incandescent body arrangement shown in Fig. 3 theincandescent body is of inverted U-shape. The central part l5 of the incandescent body hoop rests in eyes I of the two supporting wires 5, andthe legs l5 of the yoke are attached to the ends of bimetal strips 6,which in turn are attached to lead-in wires 1. Supporting wires 5 areprovided with outward bends i'l directed towards the respective bimetalstrips and serving as a counter-contact for the bimetal strips duringtheir closing movements.

The designs shown are only to be regarded as examples, and thefundamentally new arrangement disclosed by this invention may, ofcourse, be employed in a much greater number of arrangements than hasbeen described here. Although the invention has been primarily describedwith regard to electric incandescent lamps, it can be used forincandescent bodies in electric discharge tubes.

What I claim is:

1. An electric lamp comprising a flexible filament, fixed leads forconducting current to and away from the filament, a heat sensitiveelement constructed to fiex in response to variations in temperaturerigidly fixed to one of said leads and connected in series between saidone of said leads and said filament to form a part of the currentcarrying circuit through the lamp during the normal operation thereof,and means located to be contacted by said element upon fiexure thereofin response to predetermined temperature change to provide a shuntacross at least a portion of said filament.

2. An electric lamp comprising a flexible filament, fixed leads forconducting current to and away from the filament, supporting meansengaging said filament intermediate its ends, a bimetallic element fixedat one end to one of said leads and connected at its other end to oneend of said filament, said element being located with reference to saidsupporting means to flex into contact with a portion thereof to providea shunt through said supporting means across the portion of the filamentto which said element is connected.

3. A lamp as defined in claim 2 in which said 4 tact located to beengaged by said bimetallic element.

5. A lamp as defined in claim 4 in which a bimetallic element isconnected between each of said leads and the adjacent ends of thefilament and said supporting wire is provided with two contact partsprojecting in laterally opposite directions and disposed to berespectively engaged by different ones of said bimetallic elements.

6. A lamp as defined in claim 2 in which said filament is in the form ofan inverted U the upper portion of, which is supported by supportingmeans comprising two spaced wires, one of which provides a contact partlocated to be engaged by said bimetallic element.

7. A lamp as defined in claim 6 in which each REFERENCES crrsn Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,994,620 Putt v v Mar. 19, 19352,361,485 MacGregor Oct. 31, 1944 2,442,845 Davis June 8, 1948

